CVE-2026-18256CWE-863broken-access-control

CVE-2026-18256

Medium · published October 16, 2026

CVSS v3.1
4.3
EPSS
0%
Percentile
5.0
In the wild
Unconfirmed
What it is

Mattermost versions 11.10.x <= 11.10.0, 11.7.x <= 11.7.9, 11.9.x <= 11.9.1, 11.8.x <= 11.8.5 fail to properly restrict private teams from public team search results, which allows an authenticated user without permission to list private teams to disclose the ID, name, and display name of private teams via a modified team search request. Mattermost Advisory ID: MMSA-2026-00748

The record
Technical detail
CVSS v3.1
4.3 · MEDIUM
Vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
CVSS v4.0
Not supplied
EPSS
0.00162 · 5.0th percentile
Weakness
CWE-863 · Incorrect Authorization
Published
2026-10-16T12:17Z
References (1)
https://mattermost.com/security-updates · [email protected]
EPSS history
Timeline
  • 17 OCT 03:28Z
    EPSS moved — → 0%
    epss
  • 16 OCT 07:13Z
    Private team metadata disclosure via the team search API
    cvelistv5
  • 16 OCT 07:13Z
    Private team metadata disclosure via the team search API
    cvelistv5